JP2805351B2 - Power steering device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an all-hydraulic power steering device used for industrial vehicles.

(Prior Art) The conventional device shown in FIGS. 5 to 7 divides a vehicle a into a front vehicle body 1 and a rear vehicle body 2 and connects the two vehicles 1 and 2 via connection pins 3. The two vehicles 1 and 2 rotate around the pin 3. Power cylinders 4, 5 are provided on both sides of the connecting pin 3. The rod ends of the power cylinders 4, 5 are connected to the front vehicle body 1, and the bottom side thereof is connected to the rear vehicle body 2. As shown in FIG. 6, the bottom side chamber 6 of one power cylinder 4 and the rod side chamber 7 of the other power cylinder 5 communicate with each other, and the bottom side chamber 8 of the other power cylinder 5 and one power cylinder 4 Is communicated with the rod-side chamber 9.

The hydraulic circuits shown in FIG. 6 control the power cylinders 4 and 5 in this manner.

All-hydraulic steering pump linked to handle 10
A pilot pump 14 and a tank 15 are connected to 11 via flow paths 12 and 13.

The steering pump 11 thus constructed is provided with a steering wheel 10.
When the is rotated, a flow rate proportional to the rotation speed is discharged to one of the pilot flow paths 16 and 17, and the fluid in the other pilot flow path 17 or 16 is discharged to the tank.
Returning to 15, the graph of FIG. 7 shows the relationship between the rotation speed of the handle 10 and the discharge amount. As is apparent from this graph, the flow rate is not discharged from the steering pump 11 unless the steering wheel 10 becomes higher than a certain rotation speed.
When the rotation speed reaches a predetermined rotation speed, a flow rate proportional to the rotation speed is discharged, and when the rotation speed reaches a certain speed or more, the discharge amount becomes constant.

Each of the pilot flow paths 16 and 17 is connected to pilot chambers 19 and 20 provided on both sides of the steering valve 18. A supply flow path 21 and a return flow path 22 are connected to one side of the steering valve 18. The supply passage 21 communicates with the main pump 23, and the return passage 22 communicates with the tank 24. Actuator channels 25 and 26 are connected to the other side of the steering valve 18, and these actuator channels 25 and 26 are connected to the bottom chambers 6 and 8 of the power cylinders 4 and 5, respectively. .

Now, assuming that the steering wheel 10 is turned to the right, hydraulic oil proportional to the rotation speed flows to one pilot chamber 19 of the steering valve 18 via the steering oil. And the pilot room
In 19, a pilot pressure corresponding to the supply flow rate from the steering pump 11 is generated, and the steering valve 18 is switched by the action of the pilot pressure, and one actuator flow path 25 and the main pump 23 are communicated with each other. The other actuator flow path 26 and the tank 24 are communicated.

Therefore, the bottom side chamber 6 of one power cylinder 4
The pressure oil is supplied to the rod-side chamber 7 of the other power cylinder 5 and the rod-side chamber 9 of one power cylinder 4 and the bottom-side chamber 8 of the other power cylinder 5 communicate with the tank 24. As a result, one power cylinder 4 extends and the other power cylinder 5 contracts, so that the vehicle a is bent rightward. That is, the vehicle is steered to the right.

When the steering wheel 10 is turned to the left, contrary to the above, the hydraulic oil discharged from the steering pump 11 flows through the pilot passage 17 into the pilot chamber 19 of the steering valve 18.
To generate pilot pressure there. The steering valve 18 is switched by the action of the pilot pressure, and the one power cylinder 4 is contracted and the other power cylinder 5 is extended to cause the vehicle a to bend leftward by the same principle as described above. The vehicle is steered to the left.

(Problems to be Solved by the Invention) In the conventional device as described above, when the steering wheel is rotated at a low speed, the amount of discharge from the steering pump 11 is small even if the rotation angle is large. The amount of switching is also reduced. Handle 10 for that
A situation occurs in which the vehicle a is not steered so much even when the vehicle rotates greatly.

Once such a situation occurs, the correspondence between the steering wheel 10 and the vehicle a is deviated, and the so-called knob deviation that the vehicle a does not return to the straight traveling state even when the steering wheel 10 is returned to the neutral position occurs. Was.

Further, regardless of the rotation speed of the handle 10, the knob may be displaced due to oil leaks in the circuit system. If the knob is displaced in this manner, for example, the vehicle does not travel straight even though the steering wheel is returned to the neutral position, and there has been a problem that the steering stability is extremely deteriorated.

An object of the present invention is to provide a device which can automatically correct the correspondence between a steering wheel and a vehicle, even if the correspondence is shifted.

(Means for Solving the Problems) According to the present invention, a steering pump for discharging a flow rate proportional to the rotation speed of a steering wheel is connected to a pilot pump, and the steering pump is connected to a pilot chamber of a steering valve. Is switched in accordance with the pilot flow rate, while a power steering apparatus for supplying the main pump discharge oil to the power cylinder in accordance with the switching position of the steering valve is assumed.

On the premise of the above device, the device of the present invention comprises a steering wheel angle sensor for detecting a steering wheel rotation angle, a steering angle sensor for detecting a vehicle turning angle, and a steering wheel rotation angle based on signals from both sensors. A controller that calculates the relative angle between the steering angle of the vehicle and the steering angle of the vehicle, and outputs the calculation result as a correction signal; and a bypass passage that connects the pilot pump and the pilot chamber of the steering valve.
In addition, it is characterized in that it is provided with a correction solenoid valve that switches in response to the correction signal and communicates the pilot chamber of the steering valve with the pilot pump.

(Operation of the Present Invention) Since the present invention is configured as described above, the controller calculates the relative difference between the rotation angle of the steering wheel and the steering angle of the vehicle based on the signals detected by both sensors. When the relative difference occurs, the controller sends a correction signal to the correction solenoid valve. As a result, the solenoid valve for correction is switched, and the pilot pump and the pilot chamber of the steering valve are communicated to switch the steering valve.

As described above, when the correspondence between the steering wheel and the vehicle is displaced, the steering valve is switched regardless of the rotation angle of the steering wheel, so that the relative difference between the two can be automatically corrected.

(Effect of the Present Invention) According to the power steering device of the present invention, even if the correspondence between the steering wheel and the vehicle is shifted, it is automatically corrected. For example, even though the steering wheel is neutralized, The danger that the vehicle does not travel straight can be avoided.

(Embodiment of the Present Invention) In the embodiment shown in FIGS. 1 to 4, a correction solenoid valve V is connected to bypass passages 27 and 28 connecting the passages 12 and 13 and the pilot passages 16 and 17. In addition, it is characterized in that a control system for electrically controlling the solenoid valve V for correction is provided, and the other configuration is exactly the same as the conventional one.

Therefore, the same components as those in the related art are denoted by the same reference numerals as those in FIG. 6, and the detailed description thereof will be omitted, and differences from the related art will be described in detail.

The correction solenoid valve V is provided with solenoids 29 and 30 on both sides thereof. When both the solenoids 29 and 30 are not excited and the valve V is maintained at the neutral position, the bypass passages 27 and 28 are closed. When one of the solenoids is excited, the valve V
Is switched to allow one of the pilot passages 16 or 17 to communicate with the pilot pump 14 via the bypass passages 27 and 28, and the other pilot passage 17 or 16
Is communicated with the tank 15.

The switching amount of the correction solenoid valve V is proportional to the exciting current for the solenoids 29 and 30. Therefore, the larger the exciting current is, the larger the switching amount of the correction solenoid valve V is, and the larger the pilot flow rate supplied to the pilot chamber 19 or 20 is. Since the pressure in the pilot chamber increases in proportion to the pilot flow rate as described above, if the excitation current of the solenoids 29 and 30 of the correction solenoid valve V is large, the pressure in the pilot chambers 19 and 20 also increases, The switching amount of the steering valve 18 also increases accordingly. The large switching amount of the steering valve 18 means that the supply flow rate from the main pump 23 to the power cylinders 4 and 5 also increases, and the correction amount for the power cylinders also increases. Conversely, solenoid 29,
If the exciting current for 30 is small, the switching amount of the solenoid valve for correction V is also small, and consequently the correction amount for the power cylinder is also small.

The controller C is connected to the solenoids 29 and 30 of the correction solenoid valve V as described above. The controller C is connected to a steering wheel rotation angle sensor 31 for detecting the rotation angle of the steering wheel 10 and a steering angle sensor 32 for detecting the refraction angle (steering angle) of the vehicle a.

The specific configuration of the controller C thus configured is as shown in FIG.

The steering wheel rotation angle sensor 31 is provided by a differentiating unit 33 of the controller C → a first comparing unit 34 → a first solenoid for correcting the solenoid valve V for right switching via a first AND gate 35.
Connected to 29. The differentiator 33 is for differentiating the rotation angle of the handle to calculate the handle rotation speed.

The first comparison unit 34 is connected to the idling speed storage unit 36,
Judge whether 10 keeps the rotation speed more than the idling speed,
A signal is output to the first AND gate 35 when the speed is lower than that speed.

The steering angle sensor 32 for detecting the refraction angle of the vehicle a includes an amplifying unit.
37 → Connected to the first and second AND gates 35 and 40 via the second and third comparators 38 and 39. The second and third comparison sections 38 and 39 are connected to a right refraction angle limit storage section 41 in which the refraction angle limit of the vehicle a in the right turn direction is set. Also, the third comparing unit 39
Is connected to a left refraction angle limit storage unit 42 in which a limit of the refraction angle in the left turn direction is set.

Then, when the refraction angle of the vehicle a detected by the steering angle sensor 32 is within the range of the left and right refraction angle limits, the second and third comparators 38 and 39 send signals to the first and second AND gates 35 and 40. Output.

Each of the steering wheel rotation angle sensor 31 and the steering angle sensor 32 described above is also connected to the calculation unit 43. The calculation unit 43 uses signals from the sensors 31 and 32 to calculate
A relative difference between the steering wheel angle and the refraction angle (steering angle) of the vehicle is calculated, and the calculation result is output to the fourth and fifth comparison units 4 via the amplification unit 44.
5 and 46. Dead zone storage units 47 and 48 are connected to the fourth and fifth comparison units, respectively. The dead zone storage units 47 and 48 store a so-called play range of the handle 10. When the relative difference calculated by the calculation unit 43 is within the range of the play of the steering wheel 10, the fourth and fifth positions are set.
The comparison units 45 and 46 do not output signals. However, when the range of the play is exceeded, the fourth and fifth comparators 45 and 46 output a signal to that effect to the first and second AND gates 35 and 40.

 Next, the operation of this embodiment will be described.

The rotation angle signal of the steering wheel 10 detected by the sensor 31 during traveling of the vehicle is input to the differentiator 33 and the calculator 43. Also,
The refraction angle signal detected by the vehicle body refraction angle sensor 32 is input to the amplification unit 37 and the calculation unit 43.

In the differentiator 33, the rotation speed of the handle 10 is calculated,
This is input to the first comparing unit 34. Also, the first comparison unit
The signal of the idling speed storage unit 36 is input to 34, and it is determined whether or not the rotational speed of the handle 10 is in the idling region of the handle shown in FIG. If the actual steering wheel rotation speed is equal to or higher than the above-mentioned idling range, it is determined that the steering wheel 10 is currently being turned and steering is being performed, and no correction control of the knob displacement of the steering wheel 10 is performed.
This is because the following problem occurs when the correction control is performed while the steering wheel 10 is being steered. For example, if the correction control is performed while turning the vehicle by turning the steering wheel 10, the steering feeling suddenly changes simultaneously with the correction. If the steering feeling changes suddenly during steering in this way, it is possible that not only will the driver be distracted but also that it may cause an accident. Therefore, during steering when the rotation speed of the steering wheel is higher than the idling range, the signal is not output from the first comparison unit 34, the outputs of the first and second AND gates 35 and 40 are set to the 0 level, and the control for correcting the knob displacement is performed. Is to be stopped.

If the rotation speed of the steering wheel 10 is equal to or lower than the idling range, it is determined that the correction control is possible while the steering is stopped, and a signal is input to each of the AND gates 35 and 40.

The signal detected by the steering angle sensor 32 is amplified by the amplification unit 37 and input to the second and third comparison units 38 and 39. The second and third comparison units 38 and 39 have a storage unit 4 that stores the limit of the refraction angle of the vehicle body.
Signals from 1, 42 are also input. Then, the second and third comparing sections 38 and 39 determine whether or not the refraction angle of the vehicle body is within the above-mentioned limit. If the actual angle of refraction has reached the limit rotation, no further correction is possible, so that no signal is output from the second and third comparators 38 and 39, and the outputs of both AND gates 35 and 40 are at zero level. And the correction control is stopped.

An arithmetic unit 43 to which signals from the steering wheel rotation angle sensor 31 and the steering angle sensor 32 are input calculates the correspondence between the steering wheel angle and the steering angle (refraction angle) of the vehicle body, and sends the calculation result to the amplification unit 44. input. The amplification unit 44 amplifies the signal and inputs the amplified signal to the fourth and fifth comparison units 45 and 46. The fourth and fifth comparison units 45 and 46 store the dead band limit from the dead band storage units 47 and 48. The indicated signal is input. If the difference between the correspondence between the steering wheel angle and the refraction angle of the vehicle body is within the range of the dead zone shown in FIG. 3, in other words, within the range of the play of the steering wheel, it is determined that there is no knob displacement. , 2 and gate
Do not output signals to 35 and 40. Therefore, the outputs of the AND gates 35 and 40 become 0 level, and the correction control is stopped.

When the difference in the correspondence between the steering wheel angle and the refraction angle of the vehicle body exceeds the range of the dead zone, it is determined that a knob shift has occurred, and it is also determined whether the direction of the shift is rightward or leftward. . For example, if the relative difference between the two is positive, it is determined that the position has shifted to the right, and if the difference is negative, it is determined that the position has shifted to the left. Then, when it shifts to the right, the first comparing section 45 operates to operate the first AND gate.
Output the signal to 35. When it shifts to the left, a signal is output to the second AND gate 40.

As described above, when all the signals from the respective comparators are input to the first AND gate 35 or the second AND gate 40, the outputs of both AND gates 35 and 40 become one level,
Either one of the solenoid valves for correction V
The compensation control is performed by exciting 29 or 30.

The above relationship is shown in the flowchart of FIG. 4, and the flowchart will be described next.

First, in steps I to III, the steering wheel angle, the steering wheel rotation speed, and the steering angle (refraction angle) of the vehicle body are detected.

Then, in the IV step, it is determined whether or not the steering wheel rotation speed is within the range of the idling range. If it exceeds the range of the idling range, it is determined that the steering is currently being performed and the Vth
Proceeding to the step, the correction control is stopped, and the process returns to the start again. Conversely, if the rotation speed of the steering wheel is within the range of the idling range, it is determined that the correction control is possible for the time being, and the process proceeds to step VI.

In this step VI, it is determined whether or not the refraction angle of the vehicle body is within the limit. If the angle exceeds the limit, it is determined that no further correction is possible, and the process proceeds to the step V. Then, the correction control is stopped and the start is returned again. Conversely, if the refraction angle of the vehicle body is within the above-mentioned limit, the process proceeds to the VII step.

In this VII step, it is determined whether or not there is a deviation in the correspondence between the steering wheel and the vehicle body. If the deviation is within the range of the dead zone, the steering wheel 10 is merely rotating within the range of play, so that the process proceeds to the step VIII to stop the correction control and return to the start again. On the other hand, when the difference between the correspondence between the steering wheel and the vehicle body exceeds the dead zone, the process proceeds to the IX step or the X step according to the direction, and the solenoid 29 or 30 of the solenoid valve V for correction is excited. This is to execute the correction control. After executing the correction control in this way, the process returns to the start again. When the correction control is performed in such a manner, the control is fed back so as to always execute the control such that the correspondence between the steering wheel and the vehicle body does not deviate.

As described above, according to the device of this embodiment, the correspondence between the steering wheel and the vehicle body is detected, and when a shift occurs between both, the solenoid valve for correction V is operated,
The deviation can be corrected.

In addition, since the correction control is not executed during steering, the steering feeling does not suddenly change during steering.

[Brief description of the drawings]

1 to 4 show an embodiment of the present invention. FIG. 1 is a circuit diagram, FIG. 2 is a block diagram of a controller C, and FIG. 3 shows a relationship between a steering wheel angle and a refraction angle of a vehicle body. Graph,
FIG. 4 is a flowchart, FIGS. 5 to 7 relate to a conventional device, FIG. 5 is a schematic diagram showing a relationship between a vehicle body and a power cylinder, FIG. 6 is a circuit diagram, and FIG. 5 is a graph showing a relationship between a speed and a discharge amount of a steering pump. 4, 5: Power cylinder, 10: Handle, 11: Steering pump, 14: Pilot pump, 18: Steering valve, 19, 20: Pilot room, 23: Main pump, 27, 28 ... Bypass passage, V: Solenoid valve for correction, C: Controller.

Claims (1)

(57) [Claims] A steering pump for discharging a flow proportional to the rotation speed of a steering wheel is connected to a pilot pump, and the steering pump is connected to a pilot chamber of a steering valve. On the other hand, in a power steering device that supplies oil discharged from a main pump to a power cylinder in accordance with the switching position of the steering valve, a rotation angle sensor that detects a rotation angle of a steering wheel, and a steering wheel that detects a steering angle of a vehicle. An angle sensor, a controller that calculates a relative difference between a steering wheel rotation angle and a vehicle steering angle based on signals from both sensors, and outputs a calculation result as a correction signal; a pilot pump and a pilot chamber of a steering valve; Installed in the bypass passage communicating with In addition, the power steering apparatus includes a correction solenoid valve that is switched in accordance with the correction signal and communicates the pilot chamber of the steering valve with the pilot pump.